DAF LF45, LF55 Series. Instruction - page 14

©

3-1

System inspection with DAVIE XD

UPEC

DAVIE XD diagnostics manual

2

3. SYSTEM INSPECTION WITH DAVIE XD

3.1 GENERAL

If the vehicle has been modified and the

configuration changed, the electronic unit may

have to be re-programmed.

If the electronic unit is replaced, new UPEC

software must be loaded into the unit using

DAVIE.

The immobiliser code for the fuel release is

automatically "read" when the ignition is switched

on.

UPEC

3-2

©

System inspection with DAVIE XD

2

DAVIE XD diagnostics manual

3.2 ENGINE BRAKE TEST

Note:

1.

This test must be done with the engine at

operating temperature.

2.

To obtain a good comparison, ensure that

during the test neither the air-conditioning

system compressor nor the air supply

system are switched on or off.

During this test, the engine speed will be

increased and decreased while the exhaust

brake/DEB is activated.

After this, the engine speed will again be

increased and decreased, this time without the

exhaust brake/DEB being activated.

In both cases the fall in engine speed when

slowing down will be measured per second.

The ratio between the measured values with and

without activated exhaust brake/DEB will be

expressed as a percentage.

©

3-3

System inspection with DAVIE XD

UPEC

DAVIE XD diagnostics manual

2

3.3 SPEED VARIATION CONTROL TEST

One of the controls of the engine management

system is the uniform operation of the engine via

the speed variation control (this speed variation is

recorded via the crankshaft sensor).

Too large a variation in speed is prevented by

correcting the quantity of injected fuel per

cylinder.

Due to a fault in the fuel system (bad injector, fuel

leakage etc.) the fuel correction applied to a

cylinder may have increased to such an extent

that it falls outside the permitted specification.

Note:

Bear in mind the fact that a mechanical defect in

a cylinder (compression loss) may affect the fuel

correction for another cylinder that falls outside

the permitted specification.

Here the relation is as follows:

In the "speed variation control" test the fuel

correction of each cylinder is determined during a

trip cycle (a trip cycle where a high engine load is

required for a long period), on the basis of the

total fuel consumption.

The "speed variation control test" in DAVIE is one

of the diagnostic tools that can be applied in case

of complaints about fuel consumption and

reduced engine power.

Other tests are the acceleration test and plotting

a boost pressure curve; in principle these have to

be carried out before the "speed variation control

test" is carried out.

in case of compression loss of cylinder:

1

5

3

6

2

4

a positive fuel correction on cylinder:

3

6

2

4

1

5

UPEC

3-4

©

System inspection with DAVIE XD

2

DAVIE XD diagnostics manual

Рассказать друзьям